The antimicrobial effect of various metals and their salts has been known for centuries. Its germicidal effects increased its value in utensils and as jewelry. The exact process of silver's germicidal effect is still not entirely understood, although theories exist. One of these is the “oligodynamic effect,” which qualitatively explains the effect on some microorganisms, but cannot explain antiviral effects. Silver is widely used in topical gels and impregnated into bandages because of its wide-spectrum antimicrobial activity.
The oligodynamic effect is demonstrated by other metals, specifically gold, silver, copper, zinc, and bismuth. Copper is one such metal. Copper has long been used as a biostatic surface to line the bottoms of ships to protect against barnacles and mussels. It was originally used in pure form, but has since been superseded by brass and other alloys due to their lower cost and higher durability. Bacteria will not grow on a copper surface because it is biostatic. Copper alloys have become important netting materials in the aquaculture industry for the fact that they are antimicrobial and prevent biofouling and have strong structural and corrosion-resistant properties in marine environments. Organic compounds of copper are useful for preventing fouling of ships' hulls. Copper alloy touch surfaces have recently been investigated as antimicrobial surfaces in hospitals for decreasing transmission of nosocomial infections.
Numerous scientific investigations have focused on the role of the metal form of copper, and have concluded that multiple mechanisms may be possible for copper's antimicrobial effect, including increased production of reactive oxidation species such as singlet oxygen and hydroxide radicals, covalent binding of copper metal to reactive sites in enzymes and co-factors, interference with lipid bilayer transport proteins, and interaction of copper ions with moieties of microorganisms analogous to what have been proposed for silver ions.